No one contributed more to the early development of algebra than Descartes. In particular, he was able to unify arithmetic and geometry to a significant extent, by showing their mutual connections in terms of an algebraic notation. This was an achievement that eclipsed his other scientific work, and Descartes believed that algebra could serve as a model for his other enterprises. The connection between algebra and his other scientific work was explored, via a consideration of the question of method, in Descartes' first published work, the Discourse on the Method of rightly conducting one's reason and seeking the truth in the sciences, together with the Optics, the Meteorology and the Geometry which are essays in this method (1637). What we are ostensibly presented with here is a general treatise on method, to which are appended three examples of the method.